The patient exhibited symptoms of mania such as distractibility, rapid speech, grandiose delusions about replacing the president and being Alexander the Great. Laboratory tests ruled out substance use. The most likely diagnosis is bipolar disorder with psychotic features (option A) given the presentation of manic symptoms with psychotic features in the absence of substance use. Mood disorders are highly prevalent and impairing but many go undiagnosed. Conditions include major depression, bipolar disorder, and dysthymia. Treatment involves hospitalization, psychotherapy, and pharmacotherapy with antidepressants, mood stabilizers, or ECT.